<html>
    <head>
        <title>Test</title>
        <style>

  main {
    prototype: Main; // note `class Main` below
  }

        </style>
        <script>

class Main extends Element {

  #counter = 0;
  
  componentDidMount()
  {

    this.render()

  }  

  render () {
    //some comment
    this.innerHTML = `<button>inc</button> clicked <span.counter>${this.#counter}</span> times`;
  }

  ["on click at button"]  (evt,button)
  {
    ++this.#counter;
    this.render();
  }

}


        </script>
    </head>
    <body>

<main #test/>

    </body>
</html>